Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
In general, nanocomposite dielectric materials are composed of two phases: a high-dielectric (or “high-k”) inorganic nanoparticle phase and a low-dielectric (or “low-k”) polymer. By mixing these two materials on the nanometer scale, it becomes possible to combine the improved dielectric properties of the inorganic material with the dielectric strength of the polymer. The resulting composite can, in theory, store more energy than either of its components. In practice, however, the performance of such composite materials has been far below their theoretical limit.
There are two major methods of preparing nanocomposite dielectric materials. In the first method, nanoparticles are loaded into a base polymer by grinding, to give a thick mass with randomly distributed particles throughout the polymer matrix. However, only small volume fractions of particles can be effectively distributed this way. In the second method, a thin film of nanocomposite can be prepared by conventional solution casting methods, whereby the polymer and nanoparticles are both dissolved in a compatible solvent. This second method is preferred, because it can achieve higher volume fractions of particles, and thinner films, both of which yield improved capacitance.
The present disclosure appreciates that to improve the capacitance further, it would be beneficial to use electrodes with some degree of topography, because a rough or wavy surface can pack more surface area in a small package. However, existing methods for preparing nanocomposites may not be capable of coating rough or wavy surfaces in a uniform fashion. Thus, the present disclosure identifies that a method for coating rough surfaces is needed to further improve capacitance.